Gordon Brown has issued a rallying cry to his party by claiming a Tory general election victory would put the NHS at risk of becoming a US-style health system.

The prime minister made the claim in a speech as he hit the election trail ahead of last night’s first debate between the leaders of the three main political parties.

At a small campaign rally in Leeds, he sought to energise his party’s rank and file as the polls showed the Tories’ lead over Labour narrowing to as little as three points.

On a day in which Labour tried to throw the election spotlight on what they said was the “risk” the Tories posed to the NHS, Mr Brown suggested David Cameron would usher in a US-style health system.

“In the last few months, America has got rid of the old healthcare system that it had,” he said.

“We don’t want to go back to that type of system under a Conservative government.

“Labour stands for securing the recovery, protecting and improving our public services, building the industry of tomorrow and making sure we have a new politics in the country.

“We don’t want to go back to the same old Tories of the past. Let’s go out and do it.”

His upbeat speech came as a Populus poll in The Times showed Labour closing the gap on the Conservatives to just three points. Another poll showed the margin narrowing to five points.

Mr Brown dismissed the importance of such “day to day” polls but they were welcomed in the Labour camp.